Liquid ejection nozzle structure

ABSTRACT

To provide for laminar flow of liquid ejected through a nozzle structure, the surface in the region of the edge zone of the ejection duct of the nozzle is covered with a layer of crystal columns of at least 2 Mu m such that the axes of the crystal columns are essentially parallel to the axis of the ejection duct of the nozzle in the terminal region of the nozzle, the crystal columns, in a plane transverse to the axis of the nozzle, exhibiting a fine crystalline structure; the crystals are preferably made with at least one of the metals of titanium, vanadium, niobium, tantalum, chromium, molybenum, tungsten, iron, cobalt, nickle, gold, silver, copper, aluminum and platinum-type metals.

Unite Sttes at ent [191 Ruthardt I [451 Oct. 8, 1974 LIQUID EJECTIONNOZZLE STRUCTURE [75] Inventor: Rolf lRuthardt, l-Ianau, Germany [73]Assignee: W. C. Heraeus GmbH, I-lanau,

Germany [22] Filed: Sept. 26, 1972 [21] Appl. No.: 292,334

[30] Foreign Application Priority Data Sept. 30, 1971 Germany 2148772[52] US. Cl 239/591, 239/D1G. 19, 29/157 C [51] Int. Cl B05b l/00, B216151/00 [58] Field of Search 29/157 C; 239/DIG. 19,

[56] References Cited UNITED STATES PATENTS 3,533,771 10/1970 Stehl etal .1 239/591 X 3,662,399 5/1972 Yanou et al. 239/D1G. l9

FOREIGN PATENTS OR APPLICATIONS 1,373,520 8/1964 France 239/591 450,5224/1935 Great Britain... 239/602 Primary Examiner-Robert S. Ward, Jr.Attorney, Agent, or Firm-Flynn & Frishauf [5 7] ABSTRACT To provide forlaminar flow of liquid ejected through a nozzle structure, the surfacein the region of the edge zone of the ejection duct of the nozzle iscovered with a layer of crystal columns of at least 2 um such that theaxes of the crystal columns are essentially parallel to the axis of theejection duct of the nozzle in the terminal region of the nozzle, thecrystal columns, in a plane transverse to the axis of the nozzle,exhibiting a fine crystalline structure; the crystals are preferablymade with at least one of the metals of titanium, vanadium, niobium,tantalum, chromium, molybenum, tungsten, iron, cobalt, nickle, gold,silver, copper, aluminum and platinum-type metals.

10 Claims, 1 Drawing Figure LIQUID EJECTION NOZZLE STRUCTURE The presentinvention relates to a liquid ejector, or nozzle structure for liquidunder pressure.

Liquid ejectors or nozzles in which liquid is ejected under pressurefrom a duct, or nozzle structure is used in many technological fields.It is frequently desired that the liquid is ejected from the nozzle inlaminar flow. Such ejection thus, however, in many instances lead todifficulties if the liquid wets the exit zone or surface of the nozzlestructure or ejector, which tends to deviate the liquid from thepredetermined direction of the nozzle axis. Such a case arisesparticularly if the exit edge of the exit duct or nozzle structure isnot perfectly symmetrical, or geometrically exactly as designed,resulting in interference with the flow of the liquid through thenozzle. It is particularly important to maintain the accuracy andstability of the geometrical shape of the exit edge of the nozzle duct,and to prevent wetting of the edge zone of the exit surface of theejector or nozzle by the liquid being ejected.

It has previously been proposed to decrease the tendency to wet the exitsurface of nozzles by coating at least the edge zone of the exit surfaceof the nozzle with polytetrafluorethylene. Polytetrafluorethylene has,however, low resistance against creep and the stability of the geometricshape of the exit edge of the nozzle duct is insured only for arelatively short period of time.

It is an object of the present invention to provide a liquid ejector inwhich the exit zone of the nozzle or injector structure is soconstructed that unstable conditions of the geometry or shape of theexit edge of the nozzle duct are avoided.

SUBJECT MATTER OF THE PRESENT INVENTION It has been found, surprisingly,that by coating the exit surface of the nozzle structure in the regionof the exit zone of the nozzle with crystalline columns of at least 2 pmthickness, so that the axes of the crystalline columns extend in generalparallel to the axis of the exit duct, such instabilities and deviationfrom design of the nozzle structure, are avoided. The crystal columnstructure, in a plane transverse tothe axis of the nozzle duct, at theexit edge, has a fine crystalline structure. It is particularlydesirable that the crystalline columnar layer is made of a metal, andmetals which are particularly suitable for the columnar layer aretitanium, vanadium, niobium, tantalum, chromium, molybdenum, tungsten,iron, cobalt, nickel, gold, silver, copper, aluminum and platinum-typemetals; under platinum metals, the following are to be understood:platinum, palladium, rhodium, iridium, ruthenium, osmium. The resultsare particularly good when the crystalline columns are made of titanium,vanadium, niobium or chromium.

It is believed that the effect of the crystalline columnar layer, inaccordance with the present invention, and the stability of the geometryof this layer is derived from the crystalline structure of the columnarlayer itself. In the flow direction, which is essentially laminar, acoarsely crystalline, ideally single crystal structure is present,extending parallel to the laminar flow of the liquid, that is, to theaxis of the nozzle. In a plane perpendicular to the flow direction, thecrystalline columnar layer has a fine crystalline structure. Thus, onthe LII one hand, interference of laminar flow in the flow direction bychange of grain boundaries are avoided; on the other hand, the liquidcannot spread in the edge zone of the plane exit surface of the ejector,that is, perpendicular to the flow direction, and thus wetting of theedge zone by accumulation of changes in grain limits are avoided due tothe fine crystalline structure.

In accordance with the feature of the invention, the crystalline columnsare applied to a base, through which the ejector nozzle is formed, whichis preferably a metal such as steehin a vacuum of at least 10' mm Hg,preferably less than 10 mm Hg, by precipitation, preferably evaporationon the surface. In a preferred form of the process, the liquid ejectorstructure is maintained at an elevated temperature, for example in theorder of C, depending on the metal which is being evaporated on thenozzle surface.

The invention will be described by way of example with reference to theaccompanying drawing, wherein the single FIGURE illustrates a schematiccross sectional view of a liquid ejector made in accordance with thepresent invention.

The liquid ejector l is made of a base metal plate, for example steel,and is formed with an extrusion or ejection duct 2. The terminal zone ofduct 2 extends along an axis 3, transverse to the exit surface 4. Duct 2has a liquid applied therethrough, under pressure, to provide foressentially laminar flow of the liquid from the duct 2. The exit surface5 of the nozzle structure I is coated, at least in the region of theterminal zone surrounding theexit plane 4 by means of a crystallinecolumnar layer 6. The axes of the crystalline columns extend in generalparallel to axis 3 of the exit duct, at least in the region of theterminal zone. The crystalline columnar layer 6 exhibit a finecrystalline structure in a plane parallel to the exit plane 5.

The length of the crystal columns. that is, the thickness of thecrystalline layer 6 is in excess of 2 pm, preferably in excess of 6 um;the thickness is determined by designed considerations and by theprocess of application and may extend to 20 um or more, but may be lessfor various applications, for example may be between 6-12 um. i

The base plate may be of metal other than steel. such as bronze, brass,hard metal, titanium, titanium alloy, zirconium, zirconium alloy,tantalum, tantalum alloy, molybdenum, molybdenum alloy, tungsten andtungsten alloy.

I claim:

1. Liquid ejector, or nozzle structure comprising a base structural unit(1) having an exit plane (5),

and a duct (2) formed therethrough extending through the exit plane toprovide for ejection of liquid through-the structure from the exitplane, the axis of the duct being perpendicular to the exit plane in theregion of the terminal zone of the duct,

and a layer (6) applied to the exit plane (4) of the structural unit (1)of the ejector and applied at least in the region of the edge zone ofthe duct (2), said layer having a thickness of at least 2 ,um andcomprising a crystalline columnar structure in which the axes of thecrystal columns are essentially parallel to the axis (3) of the duct (2)in the exit zone of the duct, the crystal columns of the crystallinelayer (6) exhibiting a fine crystalline structure transverse to the exitsurface (5).

2. Ejector, or nozzle according to claim 1 wherein the crystal columnsare of metal.

3. Ejector, or nozzle according to claim 1 wherein the crystal columnscomprise at least one of the metals comprising the group of titanium,vanadium, niobium, tantalum, chromium, molybdenum, tungsten, iron,cobalt, nickel, gold, silver, copper, aluminum and platinum-type metals.

4. Ejector, or nozzle according to claim 3 wherein platinum metalscomprise platinum, palladium, rhodium, iridium, ruthenium, osmium.

5. Ejector, or nozzle according to claim 1 wherein the crystal columnscomprise at least one metal selected from the group of titanium,vanadium, niobium and chromium.

6. Ejector, or nozzle according to claim 1 wherein the thickness of thecrystalline columnar layer is between 2 to 20 am.

7. Ejector, or nozzle according to claim 1 wherein the structure (1)through which the duct is formed and on which the crystal columnar layer(6) is applied comprises a metal including at least one of the metals ofsteel, beonze, brass, hard metal, titanium, titanium alloy, zirconium,zirconiumalloy, tantalum, tantalum alloy, molybdenum, molybdenum alloy,tungsten and tungsten alloy.

8. Method of making a liquid ejector, or nozzle structure comprisingforming a duct (2) transverse to the thickness of a base material (1),the terminal end of the duct extending along an axis (3) transverse tothe surface (5) of the structure to form an exit plane (4);

and coating said exit surface (5) with a crystalline structure of ametal comprising at least one of the metals of the group of titanium,vanadium, niobium, tantalum, chromium, molybdenum, tungsten, iron,cobalt, nickel, gold, silver, copper, aluminum and platinum-type metals,by precipitating at least one of said metals on said exit surface (5)under a pressure of less than 10" mm Hg.

9. Method according to claim 8 including the step of maintaining thebase structure (1) through which the duct (2) is formed, at least in theregion of the exit plane (5) at an elevated temperature in the order ofabout 150 C, or higher.

10. Method according to claim 8 wherein the metal is evaporated on thebase structure at a pressure of less than 10 mm Hg.

1. Liquid ejector, or nozzle structure comprising a base structural unit(1) having an exit plane (5), and a duct (2) formed therethroughextending through the exit plane to provide for ejection of liquidthrough the structure from the exit plane, the axis of the duct beingperpendicular to the exit plane in the region of the terminal zone ofthe duct, and a layer (6) applied to the exit plane (4) of thestructural unit (1) of the ejector and applied at least in the region ofthe edge zone of the duct (2), said layer having a thickness of at least2 Mu m and comprising a crystalline columnar structure in which the axesof the crystal columns are essentially parallel to the axis (3) of theduct (2) in the exit zone of the duct, the crystal columns of thecrystalline layer (6) exhibiting a fine crystalline structure transverseto the exit surface (5).
 2. Ejector, or nozzle according to claim 1wherein the crystal columns are of metal.
 3. Ejector, or nozzleaccording to claim 1 wherein the crystal columns comprise at least oneof the metals comprising the group of titanium, vanadium, niobium,tantalum, chromium, molybdenum, tungsten, iron, cobalt, nickel, gold,silver, copper, aluminum and platinum-type metals.
 4. Ejector, or nozzleaccording to claim 3 wherein platinum metals comprise platinum,palladium, rhodium, iridium, ruthenium, osmium.
 5. Ejector, or nozzleaccording to claim 1 wherein the crystal columns comprise at least onemetal selected from the group of titanium, vanadium, niobium andchromium.
 6. Ejector, or nozzle according to claim 1 wherein thethickness of the crystalline columnar layer is between 2 to 20 Mu m. 7.Ejector, or nozzle according to claim 1 wherein the structure (1)through which the duct is formed and on which the crystal columnar layer(6) is applied comprises a metal including at least one of the metals ofsteel, beonze, brass, hard metal, titanium, titanium alloy, zirconium,zirconium alloy, tantalum, tantalum alloy, molybdenum, molybdenum alloy,tungsten and tungsten alloy.
 8. Method of making a liquid ejector, ornozzle structure comprising forming a duct (2) transverse to thethickness of a base material (1), the terminal end of the duct extendingalong an axis (3) transverse to the surface (5) of the structure to forman exit plane (4); and coating said exit surface (5) with a crystallinestructure of a metal comprising at least one of the metals of the groupof titanium, vanadium, niobium, tantalum, chromium, molybdenum,tungsten, iron, cobalt, nickel, gold, silver, copper, aluminum andplatinum-type metals, by precipitating at least one of said metals onsaid exit surface (5) under a pressure of less than 10 1 mm Hg. 9.Method according to claim 8 including the step of maintaining the basestructure (1) through which the duct (2) is formed, at least in theregion of the exit plane (5) at an elevated temperature in the order ofabout 150* C, or higher.
 10. Method according to claim 8 wherein themetal is evaporated on the base structure at a pressure of less than 104 mm Hg.